Termite Damage to Rim Joists

Risks

• Termites live in the soil but feed upon wood. If you live in an area where termites are a problem, just leaving a pile of firewood on the ground can attract the pesky critters. Wood stacked against your home’s foundation is an invitation for termites to climb on up and chew their way through the sill plate and rim joist. The distance between the soil and your home’s sill plate affects the risk of termite infestation. Depending upon the prevalence of termites in your region, your local building authority probably has a code that stipulates a minimum distance from the soil to the sill plate. Less than 6 inches of space increases the risk of termites finding their way into your home.

Signs

• If you’re observant, you may notice tracks, or small earthen tubes, on the foundation between the ground and the house. Subterranean termites need a water source to survive, so they alternately munch on your house and then make trips back to the soil for moisture. The termites will travel back and forth along these tracks. Other signs that something is amiss include settling that results in spongy or uneven floors, doors that stick and windows that don’t open with ease.

Checking for Termites

• Your home’s rim joist hides behind the boxing and siding, which protect it from the elements, so it’s difficult to get a good look at the joist from outside. To inspect it, go to your basement or crawl space, and take a bright flashlight and a long screwdriver. Locate the floor joists that stand on edge and run from one side of the house to the other. The floor joists sit on the sill plate, which is right above the foundation wall. On the outside of the floor joists, you’ll find the rim joist, which is identical in dimension to the floor joists. Look for signs of flaking or holes. Poke the rim joist with the screwdriver. If the wood is soft, if it crumbles or falls away, you probably have termites and you should call an exterminator right away.

Repairs

• The extent and cost of rim joist repairs depends upon the degree of the damage. If the termites just got started before you found and destroyed them, the rim joist might be okay. If the rim joist can no longer adequately support the wall above, it may require removal and replacement. This is a costly repair, especially if the damage is in a rim joist that runs parallel to the floor joists, since this specific rim joist bears more load than the ones running perpendicular to the floor joists. If the rim joist is in bad shape, the sill plate, floor joists and wall studs may also have damage that requires replacement or reinforcement.